Method of applying a layer of printing ink plus an additional layer on an underlay



March 7, 1961 L. PIHL 2,974,058

METHOD OF APPLYING A LAYER 0F PRINTING INK PLUS AN ADDITIONAL LAYER ONAN UNDERLAY Filed Oct. 10, 1958 fi/m-formmg layer containing water I Q\PO/JGI' Steam settah/e in/r containing hinder k solvent miscible withwater 5/ 76.]

Paper hose Pr/nting with steam settah/e ink contoin/ng' binder solventm/ec/b/e with water Coating with fi/m-form/ng layer conta/ning waterDispersion Dry/b9 oven G) G) umwlao fi-lhling Pew/17d INVENTGR:

United States Patent Lennart Pihl, Solna, Sweden, assignor to ResearchAktiebolag, Solna, Sweden, a corporation of Sweden Filed Oct. 10, 1958,Ser. No. 766,375

6 Claims. (Cl. 11715) It is a known fact that, when printing withso-called steam-settable printing inks, these inks can be fmadeto set ordry by the action of water vapour, mainly that pres-t ent in the air. Itis further known that, by lacquering after printing, the gloss of theprint can be improved; As regards lacquering, however, it is importantthat the ink, prior to the application of the lacquer, is absolutelydry, and this has previously applied to all printed surfaces since theinks are otherwise dissolved and bleed. Even when layers other than thelacquer layer have been applied, e.g., a protective layer, it haspreviously been necessary for the printing ink to have first driedbefore a further coat was applied.

One method of applying a layer of printing ink plus an additional layerhaving a lacquering action on an underlay is characterized by theinvention in that the type of printing ink used is a so-calledsteam-settable printing ink, i.e., an ink which can be hardened byapplying a liquid, or the vapour thereof, to the ink, and at the sametime the additional layer is applied to the printing ink, preferablyimmediately after the application of the printing ink, this layer at thetime of application containing such a liquid as can cause the printingink to harden or dry and which per se contains substances which form afilm on drying and have a lacquen'ng action on the tint. D Afterapplication this latter layer conveys liquid or the vapour thereof tothe undried layer of printing ink, whereby this latter is caused toharden (dry) under the lacquering layer formed during drying.

Since the application of the printing ink and the filmforming lacqueringlayer as described in the invention can be effected in what is forpractical purposes one operation, the otherwise necessary special dryingtime for the printing ink, is saved; this being a factor of very greateconomic importance when using modern printing machinery.

By the word layer or coat in the foregoing is meant each film or thelike of the material in question even if the thickness of same, e.g.,the thickness of the layer of ink is so small that its character of anactual layer is not especially marked.

This invention makes possible such printing and lacquering of paper,pasteboard or foils made from material other than paper in one operationwithout the necessity of waiting for the printing ink to dry. Suitableprinting inks for use with the invention are those in which resins,dissolved in glycols, serve as the carrier for the colour pigment andwhich, on the addition of water, are precipitated so that the inkhardens or is dried. Immediately after the application of the printingink a filmformer, 65

which can be in the form of an emulsion or dispersion of plastic in awater solution, is applied. These filmformers are known in the trade aslatices and may consist of either natural or artificial rubber products(elastomers) or plastics of different kinds dispersed or emulsified inthe water phase. After the water dispersion has been applied to the inkprinted on the underlay by means of Patented Mar. 7,1961

a roller or an airbrush in the usual method by spraying, dipping or insome other way, the printed and lacquered surface is dried by a flow ofair or by heating for instance by infra-red-dryers. '5 be applied if athicker film is required. As a result of the action between the printingink on the printed surface and the water dispersion'or emulsion of theplastics and as a result of the subsequent drying of the dispersion anonsmudge surface with a dry layer under the plastic film is 10obtained. To increase the gloss the plastic treated surface may, if sodesired, be caused to pass over a mechanical calendering device. Theinvention as described abovecan be adopted when printing on a continuousbasis 0 when printing individual sheets.

A general principle for the composition of so-called.

steam-settable-printing inks isto dissolve or in some other 5wayintroduce into a solvent resins, which latter serve as a carrier forthe actual colour pigment, and which wholy or partially precipitatetogether with the colour pigment when the solvent is mixed with water orsome other ,liquid. The ink is thus only partially miscible with water.or a similar liquid. According to the procedure described in theinvention said liquid is delivered by the still undried additionallayer, which must therefore still 2:) contain a sufficiently largecontent of such liquid and retain it sufficiently long to enable the inklayer to have dried completely.

As an example of the function of the invention a description is given ofprinting and plastic coating pasteboard.

When using a rotary printing press for letter press or dry offsetprinting a steam drying printing ink, a so-called steam settable inkcomposed of synthetic resins as the binder dissolved in glycols andcontaining pigment are employed. Printing is carried out in one or morecolours.

The next immediate stage is to use a roller running in a 35% wateremulsion of acrylonitrile polymers to apply a thin film on the ink layerjust applied. A heating arrangement with an infrared lamp placed abovethe newly printed pasteboard dries the emulsion while at the same time afurther roller applies an additional layer made up from a 50% waterdispersion of a co-polymer of a polyacrylic acid ester. After this layerhas been applied the printed material is passed through a drier, afterwhich the printed and lacquered material, in which all the appliedlayers are dry and hard, can be cut, stamped, sized etc. in lateroperations.

The invention is not, of course, limited to the example just described.In particular, as concerns the additional -layer to be applied to thelayer of ink, there are many alternatives. If the additional layerconsists ofelastomers or plastic materials, substances other than thosenamed above can be used either alone or mixed with each other or withthe dispersions. Suitable dispersions based upon acrylonitrilederivatives, styrene derivatives, polyacrylic acid derivatives,polyvinyl derivatives such as polyvinyl chloride, and others andcombinations thereof.

Moreover, thickeners may be added for instance, casein etc., orantistick materials, as dispersions of paraffin waxes andmicrocrystalline waxes.

When the additional layer is to consist of a layer for the protection ofa package, there are other possibilities depending on the purpose to beserved by this layer. For example, the additional layer may serve as aprotective layer, for example against corrosion, or serve the purpose ofmaking the underlay impervious to moisture. In all such cases thematerial of which the layer is to consist is to be so chosen that whenthe layer is applied to the layer of ink it can re'ease suliicient wateror other liquid to harden or dry the ink.

A renewed layer of dispersion can The invention is further illustratedby the accompanying drawings in which Fig. 1 is a diagrammaticcross-sectional view showing the layer of paper, the layer of steamsettable ink and the film-forming and ink-setting layer,

Fig. 2 is a flow sheet of the process showing by means of legends thesteps of first printing the paper base with the steam-settable ink, thenapplying the film-forming and ink-setting coating and finally drying,

Fig. 3 is a diagrammatic representation of a machine for successivelyprinting, coating and drying a continuous web of paper.

What I claim is:

1. A method of producing a print on a backing material which comprisesapplying to the backing material a layer of wet steam-settable printingink formed of a pigment, a binder and a binder solvent which is misciblein all proportions with water, applying on top of the unset printing inklayer a film-forming layer containing water in a quantity sufficient toprecipitate said binder, the film-forming layer also containing amaterial capable of forming a protecting layer over the ink layer, anddrying said layers.

2. The method as defined in claim 1 in which the film-forming layercontains a latex.

3. The method as defined in claim 1 in which the film-forming layercontains polyvinylchloride.

4. The method as defined in claim 1 in which the filmforming layercontains a thickener.

5. The method asdefined in claim 1 in which the film forming layercontains an antistick material.

6. The method as defined in claim 1 in which the material in saidfilm-forming layer which is capable of forming a protective layer overthe ink layer forms a water-resistant and corrosion resistant layer.

References Cited in the file of this patent UNITED STATES PATENTS

1. A METHOD OF PRODUCING A PRINT ON A BACKING MATERIAL WHICH COMPRISESAPPLYING TO THE BACKING MATERIAL A LAYER OF WET STEAM-SETTABLE PRINTINGINK FORMED OF A PIGMENT, A BINDER AND A BINDER SOLVENT WHICH IS MISCIBLEIN ALL PROPORTIONS WITH WATER, APPLYING ON TOP OF THE UNSET PRINTING INKLAYER A FILM-FORMING LAYER CONTAINING WATER IN A QUANTITY SUFFICIENT TOPRECIPITATE SAID BINDER, THE FILM-FORMING LAYER ALSO CONTAINING AMATERIAL CAPABLE OF FORMING A PROTECTING LAYER OVER THE INK LAYER, ANDDRYING SAID LAYERS.